Temperature and humidity gradients in a sheep's fleece. II. The energetic significance of transients

✍ Scribed by Ruth M. Gatenby; J.L. Monteith; J.A. Clark

• Publisher: Elsevier Science
• Year: 1983
• Weight: 859 KB
• Volume: 29
• Category: Article
• ISSN: 0002-1571
• DOI: 10.1016/0002-1571(83)90042-0

✦ Synopsis

The heat of sorption (H) of fleece samples was measured using an equilibrium method. H was greatest at low relative humidities, but even at a relative humidity of 0.20, H was only one fifth of the latent heat of vaporization of water. The temperature and humidity within the fleece of a Clun Forest ewe were monitored in four different environments. The transient heat production, due to sorption of water in the fleece, was calculated from the rate of change in relative humidity in the fleece. The heat production was generally small, partly because the relative humidity in the fleece changed slowly and partly because increases in relative humidity near the skin were compensated by decreases in the relative humidity in the outer parts of the fleece. On the basis of these measurements, the effect of rain on the heat budget of a fleeced sheep was estimated. Rain causes transient production of heat in the outer layers of a fleece, but also increases heat loss because (a) the thermal insulation of the fleece is reduced, and (b) the evaporation of rain removes latent heat. The mechanical work required when carrying rain in the fleece probably has a greater effect on the energy budget than sorption/de-sorption processes.